s390/qeth: allow cmd callbacks to return errnos

Error propagation from cmd callbacks currently works in a way where
qeth_send_control_data_cb() picks the raw HW code from the response,
and the cmd's originator later translates this into an errno.
The callback itself only returns 0 ("done") or 1 ("expect more data").

This is
1. limiting, as the only means for the callback to report an internal
error is to invent pseudo HW codes (such as IPA_RC_ENOMEM), that
the originator then needs to understand. For non-IPA callbacks, we
even provide a separate field in the IO buffer metadata (iob->rc) so
the callback can pass back a return value.
2. fragile, as the originator must take care to not translate any errno
that is returned by qeth's own IO code paths (eg -ENOMEM). Also, any
originator that forgets to translate the HW codes potentially passes
garbage back to its caller. For instance, see
commit 2aa4867198c2 ("s390/qeth: translate SETVLAN/DELVLAN errors").

Introduce a new model where all HW error translation is done within the
callback, and the callback returns
>  0, if it expects more data (as before)
== 0, on success
<  0, with an errno

Start off with converting all callbacks to the new model that either
a) pass back pseudo HW codes, or b) have a dependency on a specific
HW error code. Also convert c) the one callback that uses iob->rc, and
d) qeth_setadpparms_change_macaddr_cb() so that it can pass back an
error back to qeth_l2_request_initial_mac() even when the cmd itself
was successful.

The old model remains supported: if the callback returns 0, we still
propagate the response's HW error code back to the originator.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 3 deletions

diff --git a/drivers/s390/net/qeth_core_mpc.c b/drivers/s390/net/qeth_core_mpc.c
index 7ff221ae0a2e..e3f4866c158e 100644
--- a/drivers/s390/net/qeth_core_mpc.c
+++ b/drivers/s390/net/qeth_core_mpc.c
@@ -201,12 +201,10 @@ static const struct ipa_rc_msg qeth_ipa_rc_msg[] = {
 	{IPA_RC_LAN_OFFLINE,		"STRTLAN_LAN_DISABLED - LAN offline"},
 	{IPA_RC_VEPA_TO_VEB_TRANSITION,	"Adj. switch disabled port mode RR"},
 	{IPA_RC_INVALID_IP_VERSION2,	"Invalid IP version"},
-	{IPA_RC_ENOMEM,			"Memory problem"},
+	/* default for qeth_get_ipa_msg(): */
 	{IPA_RC_FFFF,			"Unknown Error"}
 };
 
-
-
 const char *qeth_get_ipa_msg(enum qeth_ipa_return_codes rc)
 {
 	int x;